This invention relates to a semiconductor memory device such as a flash module.
To increase the scale of memory capacity of a conventional semiconductor memory device, a method of increasing the size of each memory cell array of a flash memory may be employed. For example, the number of word lines of each memory cell array is increased from 512 to 1024.
As another method for increasing the scale of memory capacity of the conventional semiconductor memory device, the number of memory cell arrays provided in a flash memory may be increased. For example, the number of memory cell arrays is increased from one to four, or from four to eight. JP-A-2001-84777 discloses a flash memory having four memory cell array units (in this publication, a memory cell array unit not including a control circuit is referred to as “BANK”).
However, since both of the above-described methods employ development of a new flash memory (that is, the size of memory cell arrays is increased in the former method and the number of memory cell arrays is increased in the latter method), the capability of each constituent block constituting the flash memory, the layout of the flash memory and the like needs to be redesigned. In the case the flash memory is redesigned, its interface circuit needs to be redesigned, too. Therefore, both of the above-described methods will take time for product development.
Moreover, as the size of each memory cell array is increased, the evaluation time for the flash module using an LSI tester increases. For example, in the case of evaluating a memory module that is newly developed with the size of each memory cell array doubled from 512 word lines by 512 bit lines to 1024 word lines by 512 bit lines, using an LSI tester, the test time is twice that for a memory module of the conventional size. This is because, in the case of evaluating a memory module with the double number of sectors (double number of word lines), the number of times of rewriting, which is carried out on each word line, is doubled and as a result, the practical rewrite test time for the flash module using the LSI tester is doubled, too.